Advanced Technology in Food Production

ATFP: Human Consumption of Plant Foods Produced Using Genetic Engineering (GE) Technologies (2015)


Peters S, Imani J, Mahler V, Foetisch K, Kaul S, Paulus KE, Scheurer S, Vieths S, Kogel KH. Dau c 1.01 and Dau c 1.02-silenced transgenic carrot plants show reduced allergenicity to patients with carrot allergy. Transgenic Res. 2011; 20 (3): 547-556.

PubMed ID: 20798987
Study Design:
Non-Randomized Crossover Trial
C - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
To generate PR10-reduced hypoallergenic carrots by silencing either one of these genes in transgenic carrots by means of RNA interference (RNAi).
Inclusion Criteria:
Sera from carrot allergic patients.
Exclusion Criteria:
Not reported.
Description of Study Protocol:
  • Recruitment: A total of 10 patients with a history of clinically relevant carrot allergy were recruited. Recruitment methods were not described.
  • Design: Non-randomized crossover trial
  • Blinding used (if applicable): Implied with measurements
  • Intervention (if applicable): Dau c 1.01_RNAi and Dau c 1.02_ RNAi transgenic carrot roots
  • Statistical analysis: Not described.
Data Collection Summary:

Timing of Measurements 
Measurements completed once.

Dependent Variables

  • IgE-reactivity
  • Skin prick testing.

Independent Variables

Dau c 1.01_RNAi and Dau c 1.02_ RNAi transgenic carrot roots.
Description of Actual Data Sample:
  • Initial N: 10 carrot allergy patients
  • Attrition (final N): As above
  • Age: Not reported
  • Ethnicity: Not reported
  • Other relevant demographics: Not reported
  • Anthropometrics: Not reported
  • Location: Germany.
Summary of Results:

Key Findings

  • A total of 10 patients with a history of clinically relevant carrot allergy were included to test the allergenic reactivity to Dau c 1.01- and Dau c 1.02-reduced carrots
  • Patient One was mono-sensitized to Dau c 1.02, whereas all other patients (Patients Two through 10) had both Dau c 1.01- and Dau c 1.02-specific IgE
  • The IgE-reactivity pattern was reflected by the IgE immunoblot results on separated extracts of WT and two selected transgenic lines
  • Sera from all carrot allergic patients except Patient One detected the major carrot allergen Dau c 1 with an apparent molecular mass 16kDa in carrot extracts from WT and from the Dau c 1.02_RNAi transgenic line 33
  • In contrast, only sera from Patients Two and Nine, showing the strongest binding to natural Dau c 1, recognize residual Dau c 1 in Dau c 1.01_RNAi transgenic line 39
  • Four out of 10 sera tested showed IgE-binding to proteins with an apparent molecular mass between 36kDa and 98kDa, likely not yet identified carrot allergens or glycoproteins expressing IgE cross-reactive carbohydrates
  • As negative controls, a serum from one non-allergic patient and a buffer control were included.
Author Conclusion:
  • Our findings demonstrate the feasibility of creating low-allergenic food by using RNAi. This constitutes a reasonable approach to allergen avoidance.
  • Also, individual members of the PR10 gene family including Dau c 1.01 and Dau c 1.02 may play more specific roles during stress adaptation to various pathogens
  • It is not clear whether the distinct isoforms may have overlapping functions and are able to partially substitute for each other during plant defense.
Funding Source:
Government: Grants Ko 1208/18-1, Mahler Ma 1997/3-1, So 300/13-1 and Vi 165/6-1 from the German Research Foundation (DFG).
Reviewer Comments:
  • Sample size and demographic details are required: Not a representative sample
  • Inclusion and exclusion criteria, as well as recruitment methods, are not clear
  • Statistical analysis not described.
Quality Criteria Checklist: Primary Research
Relevance Questions
  1. Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) Yes
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? Yes
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? Yes
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
Validity Questions
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? Yes
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? Yes
2. Was the selection of study subjects/patients free from bias? No
  2.1. Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? No
  2.2. Were criteria applied equally to all study groups? No
  2.3. Were health, demographics, and other characteristics of subjects described? No
  2.4. Were the subjects/patients a representative sample of the relevant population? No
3. Were study groups comparable? N/A
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) N/A
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? N/A
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) N/A
  3.4. If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? N/A
  3.5. If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) N/A
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? N/A
4. Was method of handling withdrawals described? Yes
  4.1. Were follow-up methods described and the same for all groups? Yes
  4.2. Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? N/A
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? N/A
5. Was blinding used to prevent introduction of bias? Yes
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? N/A
  5.2. Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) Yes
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? N/A
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status? N/A
  5.5. In diagnostic study, were test results blinded to patient history and other test results? N/A
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? Yes
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? Yes
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? N/A
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? ???
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? N/A
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? N/A
  6.6. Were extra or unplanned treatments described? N/A
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? N/A
  6.8. In diagnostic study, were details of test administration and replication sufficient? N/A
7. Were outcomes clearly defined and the measurements valid and reliable? Yes
  7.1. Were primary and secondary endpoints described and relevant to the question? Yes
  7.2. Were nutrition measures appropriate to question and outcomes of concern? Yes
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? N/A
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? Yes
  7.5. Was the measurement of effect at an appropriate level of precision? Yes
  7.6. Were other factors accounted for (measured) that could affect outcomes? Yes
  7.7. Were the measurements conducted consistently across groups? N/A
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? No
  8.1. Were statistical analyses adequately described and the results reported appropriately? No
  8.2. Were correct statistical tests used and assumptions of test not violated? No
  8.3. Were statistics reported with levels of significance and/or confidence intervals? No
  8.4. Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? N/A
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? N/A
  8.6. Was clinical significance as well as statistical significance reported? No
  8.7. If negative findings, was a power calculation reported to address type 2 error? N/A
9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? Yes
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes